Georgina Buck

Definition of subtypes of essential thrombocythaemia and relation to polycythaemia vera based on JAK2 V617F mutation status: a prospective study

BACKGROUND An acquired V617F mutation in JAK2 occurs in most patients with polycythaemia vera, but is seen in only half those with essential thrombocythaemia and idiopathic myelofibrosis. We aimed to assess whether patients with the mutation are biologically distinct from those without, and why the same mutation is associated with different disease phenotypes. METHODS Two sensitive PCR-based methods were used to assess the JAK2 mutation status of 806 patients with essential thrombocythaemia, including 776 from the Medical Research Councils Primary Thrombocythaemia trial (MRC PT-1) and two other prospective studies. Laboratory and clinical features, response to treatment, and clinical events were compared for V617F-positive and V617F-negative patients with essential thrombocythaemia. FINDINGS Mutation-positive patients had multiple features resembling polycythaemia vera, with significantly increased haemoglobin (mean increase 9.6 g/L, 95% CI 7.6-11.6 g/L; p<0.0001), neutrophil counts (1.1x10(9)/L, 0.7-1.5x10(9)/L; p<0.0001), bone marrow erythropoiesis and granulopoiesis, more venous thromboses, and a higher rate of polycythaemic transformation than those without the mutation. Mutation-positive patients had lower serum erythropoietin (mean decrease 13.8 U/L; 95% CI, 10.8-16.9 U/L; p<0.0001) and ferritin (n=182; median 58 vs 91 mug/L; p=0.01) concentrations than did mutation-negative patients. Mutation-negative patients did, nonetheless, show many clinical and laboratory features that were characteristic of a myeloproliferative disorder. V617F-positive individuals were more sensitive to therapy with hydroxyurea, but not anagrelide, than those without the JAK2 mutation. INTERPRETATION Our results suggest that JAK2 V617F-positive essential thrombocythaemia and polycythaemia vera form a biological continuum, with the degree of erythrocytosis determined by physiological or genetic modifiers.

MPL mutations in myeloproliferative disorders: analysis of the PT-1 cohort

Activating mutations of MPL exon 10 have been described in a minority of patients with idiopathic myelofibrosis (IMF) or essential thrombocythemia (ET), but their prevalence and clinical significance are unclear. Here we demonstrate that MPL mutations outside exon 10 are uncommon in platelet cDNA and identify 4 different exon 10 mutations in granulocyte DNA from a retrospective cohort of 200 patients with ET or IMF. Allele-specific polymerase chain reaction was then used to genotype 776 samples from patients with ET entered into the PT-1 studies. MPL mutations were identified in 8.5% of JAK2 V617F(-) patients and a single V617F(+) patient. Patients carrying the W515K allele had a significantly higher allele burden than did those with the W515L allele, suggesting a functional difference between the 2 variants. Compared with V617F(+) ET patients, those with MPL mutations displayed lower hemoglobin and higher platelet levels at diagnosis, higher serum erythropoietin levels, endogenous megakaryocytic but not erythroid colony growth, and reduced bone marrow erythroid and overall cellularity. Compared with V617F(-) patients, those with MPL mutations were older with reduced bone marrow cellularity but could not be identified as a discrete clinicopathologic subgroup. MPL mutations lacked prognostic significance with respect to thrombosis, major hemorrhage, myelofibrotic transformation or survival.

Prospective outcome data on 267 unselected adult patients with Philadelphia chromosome–positive acute lymphoblastic leukemia confirms superiority of allogeneic transplantation over chemotherapy in the pre-imatinib era: results from the International ALL Trial MRC UKALLXII/ECOG2993

Prospective data on the value of allogeneic hematopoietic stem cell transplantation (alloHSCT) in Philadelphia chromosome-positive (Ph(+)) acute lymphoblastic leukemia (ALL) are limited. The UKALLXII/ECOG 2993 study evaluated the outcome of assigning alloHSCT with a sibling (sib) or matched unrelated donor (MUD) to patients younger than 55 years of age achieving complete remission (CR). The CR rate of 267 patients, median age 40, was 82%. Twenty-eight percent of patients proceeded to alloHSCT in first CR. Age older than 55 years or a pre-HSCT event were the most common reasons for failure to progress to alloHSCT. At 5 years, overall survival (OS) was 44% after sib alloHSCT, 36% after MUD alloHSCT, and 19% after chemotherapy. After adjustment for sex, age, and white blood count and excluding chemotherapy-treated patients who relapsed or died before the median time to alloHSCT, only relapse-free survival remained significantly superior in the alloHSCT group (odds ratio 0.31, 95% confidence interval 0.16-0.61). An intention-to-treat analysis, using the availability or not of a matched sibling donor, showed 5-year OS to be nonsignificantly better at 34% with a donor versus 25% with no donor. This prospective trial in adult Ph(+) ALL indicates a modest but significant benefit to alloHSCT. This trial has been registered with clinicaltrials.gov under identifier NCT00002514 and as ISRCTN77346223.

T-cell acute lymphoblastic leukemia in adults: clinical features, immunophenotype, cytogenetics, and outcome from the large randomized prospective trial (UKALL XII/ECOG 2993)

The biology and outcome of adult T-cell acute lymphoblastic leukemia are poorly understood. We present here the clinical and biologic features of 356 patients treated uniformly on the prospective trial (UKALL XII/ECOG 2993) with the aim of describing the outcome and identifying prognostic factors. Complete remission was obtained in 94% of patients, and 48% survived 5 years. Positivity of blasts for CD1a and lack of expression of CD13 were associated with better survival (P = .01 and < .001, respectively). NOTCH1 and CDKN2A mutations were seen in 61% and 42% of those tested. Complex cytogenetic abnormalities were associated with poorer survival (19% vs 51% at 5 years, P = .006). Central nervous system involvement at diagnosis did not affect survival (47% vs 48%, P = not significant). For 99 patients randomized between autograft and chemotherapy, 5-year survival was 51% in each arm. Patients with a matched sibling donor had superior 5-year survival to those without donors (61% vs 46%, chi(2), P = .02); this was the result of less relapse (25% vs 51% at 5 years, P < .001). Only 8 of 123 relapsed patients survive. This study provides a baseline for trials of new drugs, such as nelarabine, and may allow risk-adapted therapy in patients with poor-prognosis T-cell ALL.

UKALLXII/ECOG2993: addition of imatinib to a standard treatment regimen enhances long-term outcomes in Philadelphia positive acute lymphoblastic leukemia

The Philadelphia chromosome positive arm of the UKALLXII/ECOG2993 study for adult acute lymphoblastic leukemia (ALL) enrolled 266 patients between 1993 and 2003 (pre-imatinib cohort). In 2003 imatinib was introduced as a single-agent course following induction (N = 86, late imatinib). In 2005 imatinib was added to the second phase of induction (N = 89, early imatinib). The complete remission (CR) rate was 92% in the imatinib cohort vs 82% in the preimatinib cohort (P = .004). At 4 years, the overall survival (OS) of all patients in the imatinib cohort was 38% vs 22% in the preimatinib cohort (P = .003). The magnitude of the difference between the preimatinib and imatinib cohorts in event-free survival (EFS), OS, and relapse-free survival (RFS) seen in univariate analysis was even greater in the multivariate analysis. In the preimatinib cohort, 31% of those starting treatment achieved hematopoietic stem cell transplant (alloHSCT) compared with 46% in the imatinib cohort. A Cox multivariate analysis taking alloHSCT into account showed a modest additional benefit to imatinib (hazard ratio for EFS = 0.64, 95% confidence interval 0.44-0.93, P = .02), but no significant benefit for OS and RFS. Adding imatinib to standard therapy improves CR rate and long-term OS for adults with ALL. A proportion of the OS benefit derives from the fact that imatinib facilitates alloHSCT. This trial was registered at clinicaltrials.gov as NCT00002514.

Reticulin Accumulation in Essential Thrombocythemia: Prognostic Significance and Relationship to Therapy

PURPOSE Essential thrombocythemia (ET) manifests substantial interpatient heterogeneity in rates of thrombosis, hemorrhage, and disease transformation. Bone marrow histology reflects underlying disease activity in ET but many morphological features show poor reproducibility. PATIENTS AND METHODS We evaluated the clinical significance of bone marrow reticulin, a measure previously shown to have relatively high interobserver reliability, in a large, prospectively-studied cohort of ET patients. RESULTS Reticulin grade positively correlated with white blood cell (P = .05) and platelet counts (P = .0001) at diagnosis. Elevated reticulin levels at presentation predicted higher rates of arterial thrombosis (hazard ratio [HR], 1.8; 95% CI, 1.1 to 2.9; P = .01), major hemorrhage (HR, 2.0; 95% CI, 1.0 to 3.9; P = .05), and myelofibrotic transformation (HR, 5.5; 95% CI, 1.7 to 18.4; P = .0007) independently of known risk factors. Higher reticulin levels at diagnosis were associated with greater subsequent falls in hemoglobin levels in patients treated with anagrelide (P < .0001), but not in those receiving hydroxyurea (P = .9). Moreover, serial trephine specimens in patients randomly assigned to anagrelide showed significantly greater increases in reticulin grade compared with those allocated to hydroxyurea (P = .0003), and four patients who developed increased bone marrow reticulin on anagrelide showed regression of fibrosis when switched to hydroxyurea. These data suggest that patients receiving anagrelide therapy should undergo surveillance bone marrow biopsy every 2 to 3 years and that those who show substantially increasing reticulin levels are at risk of myelofibrotic transformation and may benefit from changing therapy before adverse clinical features develop. CONCLUSION Our results demonstrate that bone marrow reticulin grade at diagnosis represents an independent prognostic marker in ET, reflecting activity and/or duration of disease, with implications for the monitoring of patients receiving anagrelide.

Minimal residual disease is a significant predictor of treatment failure in non T-lineage adult acute lymphoblastic leukaemia: final results of the international trial UKALL XII/ECOG2993

The predictive value of molecular minimal residual disease (MRD) monitoring using polymerase chain reaction amplification of clone‐specific immunoglobulin or T‐cell Receptor rearrangements was analysed in 161 patients with non T‐lineage Philadelphia‐negative acute lymphoblastic leukaemia (ALL) participating in the UK arm of the international ALL trial UKALL XII/Eastern Cooperative Oncology Group (ECOG) 2993. MRD positivity (≥10−4) in patients treated with chemotherapy alone was associated with significantly shorter relapse‐free survival (RFS) at several time‐points during the first year of therapy. MRD status best discriminated outcome after phase 2 induction, when the relative risk of relapse was 8·95 (2·85–28·09)‐fold higher in MRD‐positive (≥10−4) patients and the 5‐year RFS 15% [95% confidence interval (CI) 0–40%] compared to 71% (56–85%) in MRD‐negative (<10−4) patients (P = 0·0002) When MRD was detected prior to autologous stem cell transplantation (SCT), a significantly higher rate of treatment failure was observed [5‐year RFS 25% (CI 0–55%) vs. 77% (95% CI 54–100%) in MRD‐negative/<10−4, P = 0·01] whereas in recipients of allogeneic‐SCT in first complete remission, MRD positivity pre‐transplant did not adversely affect outcome. These data provide a rationale for introducing MRD‐based risk stratification in future studies for the delineation of those at significant risk of treatment failure in whom intensification of therapy should be evaluated.

Correlation of blood counts with vascular complications in essential thrombocythemia: analysis of the prospective PT1 cohort

Essential thrombocythemia, a myeloproliferative neoplasm, is associated with increased platelet count and risk of thrombosis or hemorrhage. Cytoreductive therapy aims to normalize platelet counts despite there being only a minimal association between platelet count and complication rates. Evidence is increasing for a correlation between WBC count and thrombosis, but prospective data are lacking. In the present study, we investigated the relationship between vascular complications and 21 887 longitudinal blood counts in a prospective, multicenter cohort of 776 essential thrombocythemia patients. After correction for confounding variables, no association was seen between blood counts at diagnosis and future complications. However, platelet count outside of the normal range during follow-up was associated with an immediate risk of major hemorrhage (P = .0005) but not thrombosis (P = .7). Elevated WBC count during follow-up was correlated with thrombosis (P = .05) and major hemorrhage (P = .01). These data imply that the aim of cytoreduction in essential thrombocythemia should be to keep the platelet count, and arguably the WBC count, within the normal range. This study is registered at the International Standard Randomized Controlled Trials Number Registry (www.isrctn.org) as number 72251782.

Prognostic Implications of NOTCH1 and FBXW7 Mutations in Adults With T-Cell Acute Lymphoblastic Leukemia Treated on the MRC UKALLXII/ECOG E2993 Protocol

PURPOSE Notch pathway activation by mutations in either NOTCH1 and/or FBXW7 is one of the most common molecular events in T-cell acute lymphoblastic leukemia (T-ALL) and, in pediatric disease, predicts for favorable outcome. Their prognostic significance in adult T-ALL is unclear. We sought to evaluate the outcome according to mutation status of patients with adult T-ALL treated on the United Kingdom Acute Lymphoblastic Leukaemia XII (UKALLXII)/Eastern Cooperative Oncology Group (ECOG) E2993 protocol. METHODS NOTCH1 and FBXW7 were screened by a combination of denaturing high-performance liquid chromatography and sequencing in 88 adult patients with T-ALL treated on the UKALLXII/ECOG E2993 protocol and compared with clinical characteristics and outcome. RESULTS NOTCH1 and FBXW7 mutations were common (60% and 18%, respectively) and were not associated with age or WBC count. NOTCH1 heterodimerization domain mutations were associated with FBXW7 mutations (P = .02), and NOTCH1 proline, glutamic acid, serine, threonine (PEST) rich domain and FBXW7 mutations were mutually exclusive. There were an equal number of high- and standard-risk patients in the NOTCH1 and FBXW7 mutated (MUT) groups. Patients wild type (WT) for both markers trended toward poorer event-free survival (EFS; MUT v WT, 51% v 27%, P = .10; hazard ratio, 0.6). Analysis by each marker individually was not significantly predictive of outcome (NOTCH1 MUT v WT, EFS 49% v 34%, P = .20; FBXW7 MUT v WT, EFS 53% v 41%, P.72). CONCLUSION NOTCH1 and FBXW7 mutant-positive patients do not fare sufficiently well to warrant an individualized treatment approach in future studies.

Adverse impact of bone marrow transplantation on quality of life in acute myeloid leukaemia patients; analysis of the UK Medical Research Council AML 10 Trial.

The increasing success of intensive consolidation chemotherapy (CCT) as an alternative to bone marrow transplant (BMT) in acute myeloid leukaemia (AML) necessitates comparison of the impact on quality of life (QoL) of these two treatment modalities. Most QoL studies following BMT involve small patient numbers and provide ambivalent results. The present study examines QoL in a large number of patients 1 year from the end of treatment within the United Kingdom Medical Research Council (UK MRC) AML10 trial of BMT versus CCT. Allogeneic-BMT (Allo-BMT) was observed to have an adverse impact on most QoL dimensions compared with Autologous-BMT (A-BMT) and CCT. More patients receiving BMT had mouth dryness problems and worse sexual and social relationships, professional and leisure activities than CCT patients. QoL in A-BMT patients was less impacted than Allo-BMT. Intention-to-treat analysis showed similar results. These results indicate that a reconsideration of treatment strategies is warranted, and that further, good prospective studies are needed to evaluate more clearly the effects of these treatments in long-term survivors.